Re: [計量] 幾題計量~又要麻煩大家了!!!
※ 引述《phy610 ([空白])》之銘言：
: 1. A certain hospital was only open last week, and there was a total of
: 10 people traveling by bus to the hospital. What is the probability that
: at least two people went to the hospital in the same day?
: Ans: 1
一間醫院上週開幕，一週內有10個人搭巴士去醫院，問至少兩人同一天去醫院的機率
一週只有七天，七天各分給一個人，那剩下的三個不管挑哪天都會有一天
是至少兩人的可能，所以機率是100%也就是1
: 2. A bus trip of 450 miles would have taken 1 hour less if the average
: speed S for the trip had been greater by 5 miles per hour.
: Column A : The average speed S, in miles per hour, for the trip
: Column B : 50
: Ans: B
一台巴士開450公里用平均時速S，如果S增加5 miles，則總花費時間可以少1hr
那列式就是450 = (S+5)(t-1)
本來的t = 450/S 代回原式子解二元一次方程式，得S=-50 or 45
所以答案是B
: 3. An equiangular octagon has four sides of length 1 and four side of
: length (√2 )/ 2, arranged so that no two consecutive sides have
: the same length. What is the area of the octagon?
: Ans: 7/2
等角八邊形的四的邊是1跟另外四個邊是(√2 )/ 2，連續相鄰的邊長都不一樣
等角八邊形一個內角為135度
1
╱￣￣╲ 把八邊形中邊長為1的兩端跟對邊的兩端連接
1∣ ∣1 則可以切出四個角落是以(√2 )/ 2為斜邊的四個三角形
∣ ∣ 那再各別計算加起來就可以得到答案了
╲╴╴╱
1
: 4. If a fair die and a fair coin are tossed at the same time, what is
: the probability that the dots tossed on the face the die will be prime
: and the coin will turn up tails?
: Ans: 1/4
一個公平的骰子，也就是說骰到每個面的機率都一樣1/6
一個公平的銅板，所以正反兩面的機率都各1/2
現在問骰到的骰子面是質數(2,3,5)的機率而銅板是反面的機率是多少
3/6 x 1/2 = 1/4
: 此題意思我不太明白!!!
: 麻煩大家了!THX!!!
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